摘要

Objectives: This study aims to discover the indispensable role of skin microbiome in skin barrier health and how topical products support their functions. Introduction: Human skin is inhabited with commensal bacteria which play an indispensable role in multiple skin functions such as providing the first layer of barrier. In our study, we discovered a new mechanism in which Staphylococcus epidermidis, one of the most common skin commensals, utilizes glycerol as prebiotic to produce lactic acid. Materials / method: The ability of S. epidermidis to metabolize glycerol in vitro and in vivo to lactic acid were measured. Additionally, the impact of the glycerol ferments on skin barrier markers, such as filaggrin (FLG) and acid sphingomyelin phosphodiesterase 1 (SMPD-1), was also investigated using 2D and 3D skin culture models. Alteration of barrier properties and microbiome composition in response to topical product application were also assessed in an in vivo study using volunteers with skin dryness. Results: Our in vitro and in vivo experiments showed a dose-dependent increase in lactic acid levels upon application of increased concentrations of glycerol compared to the control. Using 2D and 3D skin culture models, we showed that the fermentation of glycerol, mainly lactic acid, upregulates the expression levels of key genes associated with skin barrier properties. Additionally, application of topical products containing glycerol supported increment of beneficial bacteria and concomitant improvements in skin barrier properties together with increased levels of ceramides and long-chain fatty acids. Conclusion: Using a combination of in vitro, in vivo and analytical methods, we have shown that commensal bacteria are capable of fermenting glycerol to impart skin benefits such as improving the skin barrier properties.